Ayelet Ganany-Padowicz

Engineering two-dimensional nonlinear photonic quasi-crystals

A known algorithm for modeling quasi-periodic lattices is used to generate two-dimensional quadratic nonlinear photonic quasi-crystals containing a set of desired discrete spectral components. This allows us to fabricate optical devices in which an arbitrary set of nonlinear optical processes can be efficient. We demonstrate this capability by fabricating two devices: a multidirectional single-frequency doubler and a multidirectional, multifrequency doubler that is capable of nearly collinear doubling of cw radiation in the optical communication C band (1530-1570 nm) through angle tuning.

All-optical polarization switch in a quadratic nonlinear photonic quasicrystal

We present an all-optical intensity-dependent polarization switch based on cascaded three-wave-mixing interactions in a quasiperiodic quadratic nonlinear photonic crystal. The polarization switching is realized by simultaneous quasiphase matching of upconversion and downconversion processes in LiNbO3 and achieves three orders of magnitude better efficiency than previous devices based on cascaded cubic nonlinearities. The switch allows extending mode-cleaning and mode-locking techniques to considerably lower input power. We demonstrate experimentally that a single linearly polarized 1550 nm fundamental wave generates a new fundamental wave of orthogonal polarization.

Compact 2D nonlinear photonic crystal source of beamlike path entangled photons

We experimentally demonstrate a compact two-photon path entanglement source based on 2D nonlinear quasi phase matching technique. Photon pairs are directly generated into well defined and easy to collect non-collinear beamlike modes.

Omnidirectional phase matching of arbitrary processes by radial quasi-periodic nonlinear photonic crystal

We investigate second-harmonic generation in a nonlinear photonic crystal having radial quasi-periodic order and continuous rotational symmetry. This device enables us to simultaneously phase match different nonlinear interactions in any arbitrary direction of propagation. We have fabricated such a crystal by electric field poling of a magnesium-doped stoichiometric LiTaO(3) and demonstrated frequency doubling of two different pump wavelengths at three different angles. Fourier coefficients were 10 times higher than that of a lattice-based multidirectional frequency doubler.

Compact 2D Nonlinear Photonic Crystal source of Beamlike Path Entangled Photons

We experimentally demonstrate a compact two-photon path entanglement source based on 2D nonlinear quasi phase matching technique. Photon pairs are directly generated into well defined and easy to collect non-collinear beamlike modes.

Generation of ultrafast visible and mid-IR pulses via adiabatic frequency conversion

A method for efficient, broadband sum and difference frequency generation of ultrafast pulses is demonstrated. Using aperiodically poled nonlinear crystals and a single step nonlinear mixing process, conversion efficiencies up to 50% are reported.

Temperature and wavelength dependent refractive index equation for stochiometric lithium tantalite

We present a new wavelength and temperature dependent refractive index equations for 0.5% MgO doped periodically poled stoichiometric LiTaO3 crystal for both extra-ordinary and ordinary polarizations. Our equations fit experimental data over a wide temperature (25-250°C) and spectral ranges: 0.35-6 ¿m for the extra-ordinary wave and 0.375-3.75 ¿m for the ordinary wave. The equations were cross validated with measurements of o-eo and e-oo interactions, involving both ordinary and extra-ordinary refractive indices. These dispersion equations are based on new measurements data derived from quasi phase matched frequency conversion experiments, and they are also in good agreement with previously published data.

Nonlinear photonic structures for all-optical deflection

We demonstrate both experimentally and numerically continuous all-optical deflection achieved in specially designed photonic structures in quadratic nonlinear materials and discuss their special properties using Fourier space analysis. We designed and manufactured the proposed structures in a Stoichiometric Lithium Tantalate crystal. The inverted domains consist of a set of arcs arranged in the propagation direction. This arrangement results in a periodic pattern in the propagation direction and a chirped pattern in the transverse direction. A second harmonic generation experiment was performed on the crystal structures to examine the phase matching properties. Varying the pump wavelength from 1545 nm to 1536 nm at 150°C resulted in continuous angular deflection of the second harmonic wave up to ~2.5°. Continuous deflection was also obtained by varying the crystal temperature at a fixed pump wavelength. These structures can be used for various all-optical deflection applications, e.g. all-optical router using two cascaded nonlinear processes: an up-conversion process of signal and control beams, where the output channel is controlled by the frequency of the controlling beam, followed by a down conversion process, creating a beam at the signal frequency in the desired channel.

All Optical Signal Processing Using Quadratic Nonlinear Photonic Crystals

All optical processes, e.g. deflection and polarization rotation, can be realized using cascaded χ(2): χ(2)interactions in one-dimensional and two-dimensional nonlinear photonic crystals. Collinear and non-collinear interactions in periodically- and quasi-periodically-modulated crystals are studied.